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Bruno · Posted: Wed Feb 29, 2012 7:23 pm Post subject: Dead Laptop? [SOLVED]

Hi All,

I need some help with a (possibly) dead HP Compaq NX6110 laptop. This morning it would not switch on, not on mains+battery, battery-only or mains-only power. No constant "main power" LED, no blinking battery-too-low-to-start-up "battery" LED, no fan or HD spinning up, no display back-light coming on, nothing. FWIW, it was powered down last night by suspending to RAM and has been plugged into the mains via the external PSU all this time. Having done this many times before, I've not previously had a problem, so I don't suspect this is the cause now.

The external PSU is still producing the required 18.5V, even when driving a 330R resistor (biggest dummy load I could find) but I can't measure the voltage when it is connected to the laptop without opening it and I don't have the special torx driver. None-the-less, I think the PSU is OK, however, I don't have another one or a spare battery to check this. Any ideas on how I can rule out the PSU for certain? Obviously a new PSU and/or a battery would help but I'm not exactly flush ATM. So with the PSU disconnected and held to my ear, on connection to the laptop, it starts to make a feint clicking sound at a rate of 4 per second. This is not typical. Also, now that it has got dark, I can see that the "battery" LED dimly flashes green at the same time as the clicks but usually when the battery is too low to start the system or it is charging, the LED glows yellow, only glowing green when the battery is fully charged.

So I'm thinking the internal power handling circuitry is a fault. Does anyone have any experience of fixing this? Without being able to have a good look inside until I get a torx driver, the Maintenance and Service guide makes reference to a DC-DC converter that can fail. Is this where the problem could be? Does anyone have any experience of fixing/replacing these? Does this repair work? I'm fairly adept at electronics and soldering, so am willing to undertake the repair. I also have a multimeter. I know I could try to get it repaired or even buy a new laptop, but I'm trying to save on repair/replacement costs. If I did take the professional repair route, wouldn't either the manufacturer or a repair shop just want to replace the whole system board? As it is over 6 years old and out of production, I don't see how it could be repaired that way.

FWIW Could the battery have caused this? It holds so little charge these days. Any help and thoughts will be much appreciated.

Dutch_Master · LXF regular Joined: Tue Mar 27, 2007 2:49 am Posts: 2354

I think your best bet would indeed be to repair it yourself. Key is to get the spec's of components inside then match those to what's available now. However, manufacturers of this type of consumer electronics aren't really generous on giving out this spec's, so Google has to be your friend...

wyliecoyoteuk · Posted: Thu Mar 01, 2012 2:38 pm Post subject:

It could well be the battery. you could try removing the battery and powering it up without it.
Also, many of these laptops have a small power daughterboard with the power connector on it, so it may just be a matter of replacing that.
I have looked at a laptop with similar issues, and the circuitry is very fine lines of copper with surface mount components, so not suitable for home repair really.
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Bruno · Posted: Thu Mar 01, 2012 2:55 pm Post subject:

Thanks for your replies Dutch_Master and wyliecoyoteuk. I tried powering up without the battery in place and nothing happened. Given its age, it is probably, as the saying goes, beyond economic repair. However, I'm writing up my PhD thesis ATM and am severely skint, hence pursuing the home repair route. BTW, fortunately, I've suffered no data loss and have other PCs to work on, I'm just not mobile any more for trips to the library.

I've since found videos and photos of how to dismantle it and what is inside it but nothing specific on the internal power handling. This model does not, however, have a power daughter board but I've seen a few videos of laptops that do, presumably to facilitate replacement of the power socket. I guess I'll get in touch with HP and see if they will forward any info... I just posted here on the chance that someone might know exactly what it is and what to do, having come across it before.

Cheers guys, I'll keep you posted.

DavidMcCrossan · LXF regular Joined: Fri Aug 19, 2005 10:46 am Posts: 241

Good luck with your thesis Bruno.

Best

David

arochester · Posted: Thu Mar 01, 2012 5:42 pm Post subject:

If all else fails, take out the Hard Drive and put it in an enclosure. It than becomes an external Hard Drive and retains all your files.

I have twice got an enclosure from ebay by searching: 2.5 sata ide hard disk enclosure. I can then put in either a SATA disk or an IDE by turning it around.

Like this: http://www.ebay.co.uk/itm/2-5-SATA-IDE-USB-Portable-Laptop-Hard-Disk-Drive-HD-PC-Cover-Caddy-Enclosure-/170750542078?pt=UK_Collectables_HardDriveEnclosures_RL&hash=item27c18680fe#ht_2328wt_1089 ...although it might disappear...

Weatherlawyer · Posted: Mon Mar 05, 2012 7:43 am Post subject:

Would driver updates have done this?
I can't imagine how they would circumvent the BIOS though.
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Bruno · Posted: Wed Mar 07, 2012 4:02 pm Post subject:

Hi Folks,

Firstly, a big thanks to DavidMcCrossan for your wishes, they are much appreciated. At times the thesis has been a struggle but I'm getting there now.

Next, I'm sorry to report that I think this laptop problem has beaten me. I had hoped it would be as easy as fixing my boiler (also would not start up, so I downloaded the data sheet, bought a multimeter and followed the probe tests until the fault was identified as the ignition PCB, which was suffering from nothing more serious than a dry joint) but no such luck. I can confirm for those interested that there appears to be a short circuit on the system board that is tripping up the PSU as there is only about 350 mV across the terminals once the PSU is connected to the laptop. I presume the 4 Hz clicking is the PSU trying to restart itself, only to encounter the short circuit again and shut down. Powering up with another PSU results in that PSU shutting down until its mains supply has been interrupted.

I did find a few data sheets on the power controller chips and the power transistors used in the laptop and there are a few pads on the circuit board close by these components, presumably for probe tips. I could not find the correct voltages on the outputs that I tried, though. It's pretty difficult to fault-find without a proper circuit diagram, as tracks can be on the back side or buried in multiple layers. Replacing something on the board would be tricky, too, as my soldering iron is a bit of a blunt instrument. A 30+ leg SMD chip, such as the power controllers, would require specialist tools. It just grates a bit because I feel that the solution may be trivial, like a new power transistor for a few pence. It would also have been nice to see all the power stuff on a separate board.

Any way, I still have a working desktop, so options are:
1) Make do with a public workstation PC and a USB stick when I visit the library.
2) A new (I think) system board for 120 quid or a reconditioned system board for 55 quid plus 39 quid for a new battery.
3) A new or reconditioned laptop.

I think I'll try 1) for now, but if I go for 2) later, would anybody be interested in a home laptop repair success story, should I be in a position to tell one? We're often told it can't be done.

Bruno · Posted: Wed Mar 07, 2012 4:10 pm Post subject:

PS: arochester, I'm already there with the 2.5" enclosures but it is such a good idea, I'm glad you shared. I sync the laptop and the desktop with unison, that's why data loss wasn't a problem but I did extract the drive to double-check and recovered my latest version of a fish pie recipe.

Weatherlawyer, it's unlikely, as one should get at least something if the power system works. Also, no driver or BIOS updates have been performed recently but thanks for asking.

Weatherlawyer · Posted: Fri Mar 09, 2012 12:41 am Post subject:

You might get some help from uk.d-i-y -a Usenet group with a few bods into electronics.
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Bruno · Posted: Mon Mar 12, 2012 5:33 pm Post subject:

OK, so I've managed to find a refurbished motherboard on ebay for 30 quid, pretty good so far. However, upon installation, it too suffers from the same problem when I try to power it up (mains only). The vendor happened to have two of these boards and after I reported the first as faulty, they will be sending me the second free of charge, so good news there.

However, I cannot escape the feeling that my PSU might have killed it. The vendor did sell the board as tested and working but I'm suspicious of the PSU as the problems I am having are power related and it is the common factor. The PSU is giving the correct output voltage with no load connected but I can't tell what it is doing under load or see any transient behaviour as I don't have a 'scope.

Has anyone seen a laptop PSU trash a motherboard before? Even if the PSU was assumed to be working correctly?

I think the plan of action for the new board is to connect the minimum to it (probably just the fan and the heat sink) and power it up with a new, universal laptop PSU and see if it lights. Then add more components, one at a time. Any advice will be gratefully received.

arochester · Posted: Mon Mar 12, 2012 5:55 pm Post subject:

Ouch!

Did you buy a "naked" motherboard? I recently bought a base unit for £14.99. OK I had to transplant screen module, Hard Drive, RAM, wireless card etc. Works fine. The magic words for a base unit are: Boots to BIOS

Base units for the HP Compaq NX6110 are available for a few quid more than you paid. Like this one: http://www.ebay.co.uk/itm/HP-Compaq-NX6110-Motherboard-CPU-RAM-Bottom-Base-REF-105-/110840553554?pt=UK_Computing_LaptopMotherboards_CPUs_CA&hash=item19ce9ca052#ht_2989wt_702 . The photo shows the BIOS...

NO BOOT=NO BUY!

Bruno · Posted: Mon Mar 12, 2012 7:53 pm Post subject:

Yes, it was a naked motherboard, apart from a CPU and a Modem. Thanks for the link, hopefully I won't need it but it is worth having as a plan B.

Do you have any tips on powering up the MoBo when I get it? I want to minimise the amount of handling and connecting I need to do before the first power up, so I can be sure I haven't damaged it. I presume it will do no harm to power it up without the screen connected, but is this true? Do I need at least 1 RAM card installed? I was also planning on not connecting the HD or optical drives.

dandnsmith · Posted: Tue Mar 13, 2012 1:06 pm Post subject:

The Magic Words have already been said - 'boot to BIOS'

The screen isn't strictly necessary - but will you know if it has booted without? I've recently been through this exercise (but not with a laptop mobo), and found that you cannot rely on HDDs rotation, fans turning - but an audible POST report will support.
If you don't get one, then you need a visual aid to tell whether anything happens (meaningful) - and that is the only way.
A HDD isn't needed for this verification, nor are optical media.

HTH
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Derek

Bruno · Posted: Sun Mar 18, 2012 3:45 pm Post subject:

Hi Folks,

I'm pleased to be able to report that my laptop is now back from the dead.

On receipt of the second board, I ordered a new, unbranded PSU from Amazon Marketplace for an absolute steal of a price at £5.18, which came yesterday, so I can hopefully avoid any damage by a PSU that may be faulty. Then I carefully unpacked the board and installed one RAM card, the heat-sink and fan and checked the output of the new PSU was OK, then connected the two together. The board powered up just fine whilst resting on a piece of newspaper.

So for anyone attempting the same who, like me, isn't well versed in laptop repair: The strategy of powering up the board after minimal handling and installation of other parts had no ill effect on the computer, so it seems to be a good idea (especially with used parts) as one can verify all is working on receipt, rather than after a full fitting finding that, if it doesn't work, one is unable to determine if it was dead before shipping, dead on arrival or killed during installation. I also added one component at a time and checked if it still powered up between additions, just in case they had caused the problem but none were encountered.

What also helped in this process was a Service and Repair PDF available for download from HP that details the dismantling procedure and (for those like me who can be impatient when fixing things) getting the correct tools if you don't already have them. For this project I added a set of torx drivers, a set of hexagonal nut drivers (for removing the jack posts used to fasten the VGA D-sub connector to the chassis) and a can of compressed gas for dust blowing to tool kit. I also recommend a set of standard screw drivers, a multimeter, a little bottle of isopropanol and some tissues/cotton buds for cleaning thermal paste from chips and heat-sinks, some thermal paste to reapply to heat-sinks, lots of antistatic bags to put components in when you have removed them and an antistatic wrist band.

So considering that the original battery is also questionable, I've decided to treat myself to a new one for £20 from Amazon Marketplace, which should hopefully arrive tomorrow. So all in all, I'm rather happy.

PS I now have a contender for a computer that resembles Trigger's broom, as other components (RAM, HD, WiFi) have also been upgraded since it was new.

PPS Thanks to all who shared their thoughts whilst helping me through this, your comments are much appreciated.